Molecular Membrane and Organelle Biology

How Cells Digest Themselves

Two fluorescence-labeled proteins (green and blue) bind to the artificial membrane and change its form (red). Small ... [more]

Two fluorescence-labeled proteins (green and blue) bind to the artificial membrane and change its form (red). Small vesicles emerge. The picture in white shows an overlap of the single images. [less]

Two fluorescence-labeled proteins (green and blue) bind to the artificial membrane and change its form (red). Small vesicles emerge. The picture in white shows an overlap of the single images.

The reaction chambers of a cell (organelles) fulfill different cellular and chemical processes such as the degradation of waste products. Thomas Wollert and his team investigate how cell organelles obtain their three-dimensional form and remain “in shape” – because for the scientists the organelles’ form is the key to understanding their function.

Envelope-like membranes shield the cell organelles and ensure that they can function. How do the organelles obtain and keep their shape? Given that the curvature of a membrane is based on the complex interaction of many proteins, it can hardly be explored by conventional methods. Thomas Wollert and his colleagues are assembling synthetic, fluorescence-labeled proteins at artificial membranes. With the aid of this construct, they can study the spatial and temporal interactions of individual components. In this way, the scientists have already been able to elucidate central membrane inversion processes in cellular vesicle formation.

Recycling inside the cell

Now, the scientists want to focus on autophagy. During this process, cells devour their own parts. The starting point is a bowl-shaped membrane that grows and becomes more and more curved. In doing so, it randomly surrounds parts of the cell interior including whole organelles, until they are enclosed completely. Then, these autophagosomes are degraded and the cell can recycle the released nutrients.

Degradation – maybe a therapy?

Even at the beginning of life, autophagy is essential: After the separation of the umbilical cord and until the first meal, it ensures the survival of the newborn. A detailed understanding of this process could also lead to new therapies for Alzheimer’s or Parkinson’s disease. In these neurodegenerative diseases, toxic protein clumps in the brain emerge that could be degraded via autophagy.